Tton of hew tore



Sept. 2. 1924;

PROCESS AND 1',506,761 s. MACPHERSON APPARATUS FOR TESTING DIELECTRIC MATERIALS 2 Shauna-Shes. 1

Filed Sam. 2. 19 20 Inventor:

Sept. 2. 1924. 1,506,761

B MACPHERSON PROCESS AND APPARATUS FOR TESTING DKELECIRLC MATERIALS Filed Sept. 1920 2 Sheets-Sheet 2 Inventor.

Patented Sept 2, i924.

FROCIEES AND AP! ARA'EUS TESTIEG .T IE'EJ-EG'YRIG HEATEEm '1 13:1 iizi'wi i! minis-'1 in parm'm Fm- 1. mg insiziuiin matvi'inib and ii i wimiialig mm. the i'c-s ing Hi (4% (DREW-i244: 1H1 be used in making fiiiQii'iCiil i-uwim fijihChiC oiemcn in N10 iJl-"iiPi [L'iiiziw' cemimawrs usiisiilv mad Hf fil fi. m2 essify fer i MILE; such vmirriL-iw :iipalrticuizu'iy WiiQIG mica is in he usui. Th: iHVCJti'iiNl, them farm wiii Em i'l IPii} iiiwiu (i in eonnectiun Wii'i'i a ipumtus dasigneii apt-- ciall for tafiiing' the ditvififliEiC atreis zt'h of sheets (if mica, iiltiiou zh it wiii wi'u'i iy he lmiiersimni that fhir': HPPH (m and liar Lvu'e'i prom provided i i: 4 fitqiiflii i' f'ipjfihCil iF in iim imimg u; eieufric iimimi-f:

The. pX'OCG/w'b of pri-pziring mica delimit??? for assembly with iin fnii or MR9? inriiiwrt ing elements in fwum a wu'uienser imziuales the spiitiiing of fin; wicn inn) siiwm of i'iw required thickness and the dining out m cutting of these sheets to the req'uii'ed shape and dimensions. These silvers of] mini 7H3. very thin, usually about me nnwiiiumsamiin of an inch in thickness. and since mica main rail frail mmthmiczflly :1 i'wy Uliimiffiai'ifil pcrventzigc of thew mica Fi'IIEKLS miiiuin hole. flaw, or impvrfection which IHIdLP-i thelnunfit for use in a condenser. If one of these defective eimnents is assembiei'i in thF' condenser stack it will permit an M00- irical iiischur P through the hole or other flaw or imper. action and this discharge will short circuit, and therefore ruin, the emire condenser. It is impraciicahl to detoct these flaws my a vimmi insywriimi ami ii ham Eh???" iii-v. been PI'OIHiHWFi iKTPH' ffTiQ in w it lih itj eiemenis before fiat-y em: assembled in the condenssir stink is swim-ding them in :2 iii.- fiBL'il'iL' si'i'ain considerably greaier than that in which Hwy are subjected in he condenser. Such a testing aperaiion eliminaies the imwiii: ii. 0-; izilm i i I i): 1hrizaica shee't is P91" 1d how 4: Nil, inf if it given down 213. 021

mini

its

n zi-lciiliienal V in ihild Hist: 1 'hiii shscts is; ammimmi. iiimiiy mi 01 tiw sheets will he broken dawn. I! is evident i :11, ibis breaii-qiuwn is n01 due simg iy in v2 iippiiflliifil'k if Hie testing p0- te-ni'iali sincv sheds that. suwessfuiiy with stand a lung mntinued application of the ivsiing {)(Iiifliifll meal: in whnn tesie Piuc i'ic s imgth of IE! FEQMHLVH" ikbfPii, and thy. ii imposes a strain c-n i! We i iiifielltii which not only is of ne V'Ahi from 3 Eating sta'ndpaint bat is detrimental the filaments tested I I have determined hat ibis rasuii: is due to film fad that the movabks electrode of the tesiing u paraius is bmughi inte centact with Lin: mim sheet under ast a? i.% moved ai y man said siieeh 1.1m fim' 0f ciu'mnt hie-tween ii i .31 gassefi b}; the pm 7 i'wt and 3380 b the presence at an 113: guy uni} a brush discharge etc is through the air gap betwaen the mica and the .mova'nia tm'minal which generaws an a apreciable ammmt at heal; s'mi The inrentinn also is directed tn rmprmrrnents in apparatus of this character 1h" signed to contribute in the safety and 0012p fort nf the operater.

The nature of the inventinn will he reeih ily understood from the following description when read in connection with the avcompanying drawings. anti the novel few tnres will be particularly pninteri ant in the appended claims.

Referring now m the drawings.

Figure l is n prr periive i'lPW (if an an parntns rnnsirmrierl in iH'llH'iilLiI-JR with 11m resent inventinn. rertnin n? the e ement-a in indicated diagrammatic-ah and Fig. 2 is a vertiral cross sef'timml vie illustrating another form m." apparatus rmhmlying the present in'vcnt inn, rerinin part of this apparatus also lXlTti! iniiiwitel (lingruinina icalhn Referring first. to Fig. l the n there shown rnmprisee a hash t in; ins: materiel :lesig'nvil in he sernreal 7 suitable supper-t. sin-h as a he -ii m tnnir. A stntirtmnry metallic plate nr TH l .12! '2 mnnnteil en the fer-ward en 'l nit the lmse :5. Secnrerl to the rearward edge at this ha hy a hinge 4 is an arm or plate 5 (ti hamlet-- ing material, tn the under sni'fnrn if \vliivh is secnrerl nnnther metnllir mntari plate terminal 6. A groove nr revwxs 7 is mi the stetirmziry terminal ii at n prngwr =5 r to IP PiVQ the mire sheer N in he il'?' iii. this reress thus serving as a re m-ami e! mezms for enabling the nperntiir in hu-r the mica sheet rgnirhly in te ting pmir'mnw The upper cnnteet or testing: terminal it is of the same shape and dimensions as the an tive arch of the mire sheet, tn he iestmi. it be ing understood that by the mm arm ls mmmi that area snhjectiul $0 a helm-tri train when the mi a element is in men in ii condenser: In Fig. l the a rive urn pi Th! mica sheet the central pin-lien f the sheet em'lnsvci within t e inn en linrs. thic hrin; snrrnninlezl h nn :n-tiw mm gin.

Th0 ll'liiif'iS 3 and (3 i'm'n: the terminals a high pntentinl testingg'r" *nii nn l in:- t pnrgipss of moving the upper tenants? in and nut; n? r ntnrt with the n iii." plate lTHHIlEl'iE'l in; means in 1:21 w rod F to n lever 9 that is inicrnnn-il :m n

the mica sheet.

standard 10 the lever hein connected by a link 11 to a rearlle 12 whirl is hinged at ii? in a base 14. A spring 15 eunneted at. mu end tn the lower eml of the link 8 and nil its uypesile eml to the base 14 normally hnlels the terminal 6 in cnnizuit with the tier-- minal 3. When however the i'nrward end of the trezuile is depressed. this movement is: trunsniitlml through the linl: l. lever 9 and mi 8 in the plate thns raising the plate are lifting the contact 6 away from its cnopernting cnntavt P5" terminal 3.

The cirvnit crmtrnliing mnnevtinns are so arranged that; the testing potential is im pressed nernss the terminals 5% and 6 nnly efter the have been relatively moved into firm engagement with the nppnsitv faces m the mica sheet M. and this pntentiel is auturnatically cut off i'rnm the terminals again before they are relatively mnveii tn release This result; is nhtninerl in the cnnstrnctinn shown hr nmm'iting the r-nntrnlling switch For the circnit-s' 0n the trea flle That the high pntential rircnii; eomprises a seconiilnry coil l? 0f an induction wait or transformer, this coil heing energized irnm a low patentiai circuit romnrising a primary esil {F an interrupter l9 a hat-terry or other senrre of direct current Eli hand switch 21. and :1 feet switch that i-nmprises two parallel plate" -22, and 'n her 93, {30th 2* '2 lates 22 h e SPPUIQfl in tin t eeiile 1:; A rule the her ES secured whirl: is pivoted 'irniettv is held ing- 96 ininsnlntingplate 11 the tremlle 33, at if in 21- re (i pnstinn h n m, tea-gm i'lilZWCPTI the plate 3% i part of ihn trez'zclle. nitahle mni'inrtn mnect the tire plates BE-22 with the i'inttery E and mil it? A r-vmrlensnr 25 is incinrlerl in the high potential rirrnit in limit the rnrrent tlnwinn therein. wi l 22 visnsi iruiimtinn nf the mirrrnt iinw is :ifinri eat irv i volt meter )9 slmnleii m'rnss n Vflrr' -lc i tamrn Ilii. tanre 3H may n her an winner-mi suit or riiscnnnnrtnci in llvfl'izr's it it wiinii in u ing this apparatus :i z-urviing' tn the gireseni prm-ess :he riperntm' first depresse the trcnelle E2 in raise the upper nnntart m terminal *3 intu its npperlnnst pnsitimn the switches 21 and 31 being rinsed. The nperzit-or nest pla es a. mine short or film to he taster] in th rece s 7 in the stntinnnry tcrminnl i. as indicated at M. Fig. l The witch 29 at this time held Open lue w f: t that the plate 2-? held in its relic-3w the pressure en the tri-eilh- IE2 thus permitting the strong spring li= tn lvnvm' iii! ii'tlnitir zl (i into ens! inrnl n th the itlil'ii illEt'i :asnl when this s? ir'irnt has l m mmplriml the Ol'KlillHl' win his font,

from. or further relieves pressure on. the hinged plate 24. thus enabling the light spring: it; to rais the but 23 into cngego ment with the contacts 2Q- -33 to cl se the primary circuit. The high potential circuit is immediately energized and the tes ing poteuial consequently is impressed across the terminals 3 and 6, thus applying the desired dielectric strain to the mica Film M.

it the mice sheet successfully withstands the test the operator will observe that no movement of the needle of the volt meter 29 occurs. Usually. however. the testing potential is suliicient to jump across the inactive margin to the adjucent wulls of the recess in the metallic terminal 3, and the operator upon seeing this electrical dischurgo around the margin of the mica sheet will l'IZifH; that the sheet is good. it. hower the sheet breaks down during the test. no c ectricnl discharge will be seen around the nuirgin of the sheet and the operator thus will know that the sheet in defective; if the volt meter .29 is used. the flow of current through the high potential circuit caused by the breaking down of the element under test will produce a movement of the volt meter needle which will indicate to the operator that the sheet is imperfect.

l sually the volt meter is not used but the operator watches the electrical discharge that takes place and determines in this man ner Whether or not the mica sheet is clefective. The act of watching this discharge is trying to the eyes. and for the purpose of relieving this strain a sheet 32 of sonic translucent material having suitable protectire characteristics preferably iis secured to the upper surface of the arm 5 and pro jects at the front and sides beyond the c0ntact, 6. so that the operator sees the discharge through this translucent material. This sheet may consist of any one of n vari ety of materials. such as amber colored glass or celluloid. lcad glass. or the like.

Whcn the test has been completed the operator again depresses the trundle and the first eil'cct of this depressing movement is to force the hinged plate 24 downwardly against the action of the light spring 26, thus i'noving the her 23 out of contact with. the contacts fib -.22. breaking the primary circuit. and consequently Llcenergizing the high potential circuit. This action takes plant: before the depressing movement of th cudlc i2 is lit-gun. and consequently the t sting potential is ut oil from the Q91 nzinnls L- ,nntl l iict'orc the upper terminal i rgisetl out of content: with the mica film M. It. will thus be observed that the test potential is applied to the mice film only after the terminaisere relatively moved into firm contact therewith and that it is out ofi from these terminals again before they are to control the primary circuit.

relatively moved to release the Elm. Any possibility of the presence of an air di clwtric between the mica illITt find one of lhc testing: terminals therefore avoided Not only does this give a for more reliable tor-2t of the dielectric strength of the sheetmziteriziis being: tested. but th fact that the testing terminals are brought into engage iuent with the mica sheet by means of a spring ensures the application of uniform pressure to each sheet that is tested and thus contributes to greater accuracy in results. A further advantage of this construction is that it protects the operator from injury since the testing terminals are dead at all times when the operator has any occasion to touch them.

Another apparatus embodying certain features of the present invention, and with which the process of the present invention can he conveniently practised. is illustrated in Fig. This apparatus comprises a. metallic table or plate 40 on which the mica films M are placed and which forms one terminal of the testing circuit. The other terminal 41 has a plane face of the size and shape of the active urea of one of the mica sheets to he tested and it forms art of a hand implen'ient. This terminal is secured by a screw 39 to the lower end of a stud 42 ot the upper end of which is formed a split sot 43 to receive a ball end 44 secured in the lower end of a plunger 45. The two parts of the socket 43 are. secured together by screw 46 anal this socket is provided with a. flaring portion 47 to engage :1 washer 48 on the lower end of the plunger and thus limit the universal movement provided by; the ball and socket, joint.

The plunger 45 is mounted to slide freely in a handle 49, this sliding movement being limited by a pin 50 that projects through 2: slot the plunger '15. Normally the plunger 45 is held at the lower limit of its movement relatively to the handle. by means of :1 spring 52 which bears on the upper endof the longer.

This spring and the relative movement between the plunger and handle are utilized For this purpose the spring 52 bears at its lower end on a metallic washer that is secured on r the upper end of the plunger by a nut on a. screw 54 which is threaded into the I n plunger. The upper end of this spring bears on a. metallic colln r which. is set into the upper end of the socket in which the plunger is mounted. and a terminal screw 56 project ing through one. side of the. handle is threaded into this collar. A screw 57 is threaded axially into the upper end of the handle in nlinenient. with the screw 54, the;

adjacent ends of these. two members being normally separated by a substantial gap, on a pair of nuts 58 threaded on the screw 57 screw 56.

The summdary cirmzil r-plnpria s 2P4- ondary mil 6?}. fha mrminals of which are (OIlXlPL'TP(l, raspecfiwly. tn The talvle 49 and scraw 39. and llfljl'Klllbli IEELClflINQ 64 he in; included in this circuit to limit the nnrrent flnw'mg tharfl'hrough,

In using this apparatus the mica films to be tesl'evl are laid ml the metallic plate 40 in spaced raluticnallip, The operator than grasps film handle in and places: the tfi'minal 41 on the central pm'iinn of one of the mica she ts and presses downwardly an the handle) This pmasure anmpressfis the spring 52, closing the awitch 545'Y. ihus energizing the snronciar rircuif ancl impressing theiesiing pntential across the mica sheet. If. the operator sees a discharge frum the terminal 41 around the. erlge of the mica sheet he knnwa that the sheefi. is: 3006, wlwraas if snnh a rliachar ze is absent he lmnws that the sheet in slefwitlve. soon as; the pressure on the l'mmllP 4-9 is rcleasad the spring 52 spans the switch 54- 57 thus hrraking the primary circnif and therafura deenergizing the senonclary circuit. opr rator than repeats this operat-lcn on the other mica sheets and disnards those that are defective.

The testing operation can be performed very r apidly with this! apparatus. The armnecrinn of the terminal 4] to the handla through a hall and socket joint is of ad Vania; in en ulfing a gnnd mmacl hPiWPBfi thi ierminal and the mica. sheet not-with standing minor variations in (he angular position of tha handle with referance tn the plate 40. This apparatus also has tho same advantage as that hf the apparatus above dera-rilwd in applying flu 'wsfing potential to the mic-a film only after the film is firmly lwld between lhP Testing #rrminals. and f matting of? lhls puivnfial again hnfm'e l'lw film 1 ralaaaed lay {lw l'nrminalS.

The hamllu "19 preferably in provided Wilh a disk-like extension 66 at its lnwvr 0nd to prevent the ops'ramrs hand from sliding down arcillvntally lair; centart \vil'h lhe movable trrminal 4% or the parts alnctril-all ('onnonted tlwretn.

While I have heroin Shawn and (lesc'ribed flu he! amhmlimrenls (sf llw invnntion nl' Whlill I- am ai present awarm it will be un- :lr-rslnwl by Thane skilled in Hula art that the invention may be umbndignl ln many niher forms of apparatus without departing from thv spirit or scope af this %r.wm.im'1 and that the prawns herein dim-ham i; indwpenklani of any Fperifiv apmratna hm may la ljla tisml with the Al a? a k warm-iv form? of apparama. ll la n rlm'stoml that "while l last-r law in rVlHEWl to mica as (h? s-pmllic' @livlwtrw malarial 21 ha tested aim-e H J11 Pl -'l!j at wrfurming this fasting oparaiims arm arlll-nlarly where mica is tn be in-ml. nvli' wa il'n- IHQPHIS nor apparatus lwrvin lllve-lwsml are iimltml tn tlm tesling of mlva lml nilwr iie lwtrir: matvrlals are l'lw eql'ivaleni i mir'a riu far a; this invention is mnrernml.

Vhat is vlaimml as new;

1. A mir'a lesling apparatnz mat a'lsi in eoznhinalinn, relatively morn fauna nals for engaging opposite fa m nl' a sheaf of miva a high pntantial rvnil unnneannl with said terminals. a trrallir wlnartell with said frrminals. far relallwl v nmving them. a. spring (fillflQi'lQ'l with -a'ul lraadle fdr holding it at nne limit hf il mmanwn, a switah aonfmlllng sa d r-iwuil and lmnuntefi on said tremile and a spring nor mall holding said switvh in a pawn-larmined condition.

2. A. mica testing apparal'na cnmprisin in combination re'iaiivaly mmnl'ala l'&?F':'Tinals for engaging oppnsit? farm of a shank of mica a high polenclal clrmii -1'11li12 f04l with sald terminals. 2 lrr-alll mum feel with said terminals: far rvlafivy m rang them, a spring ((lflllti'ltll m saifi tr-eazlln tending to hold sail? lax-annals in thrlr miva engaging positionq a swiirh mounted me said treadle and controlling said high nlnnlla rsircuit, and a spring normally holdin sail? switch closed.

3. A testing apparatus mrnprising, in combination, a pair of ffilmhmll adapiad tn engage the opposile faces of a Rhee? m5 al electric, one of said terminals mansion less than the fiorrvspmmlng mnnmr sion of the sheet providing a margin ms the sheet separating the terminala from aanh other, means for impressing; a high om tial on said terminals across Said rllnlavirr' of an order t0 cause brushing am'annl tha margin when the shrwt in g and am? a lnrrent member mounted between the sh se :er and the locatian of brushing whinh said brushing may he ah'zurvwfl 4. A testing apparatus (a qpriaing; la comhinafinn, relatively muvahle mafia? blocks forming terminal vunnacted in a smlrce of high potential, One of aaill l'flmrk having an arenfiess ban laat all ilw wither and the larger black being pmvided with recnss/ fox-mad therein in reraive sail"? 15,1 5. the smaller blm'k having: an arm loss; ill-an that of the sheet and rea er 5. The herein-(lesrribed mvl'lmll A ta: 7 a sheet of insulation Which cunaists in upplying a high potential through the sheet upon the central portion thereof only, of such an order as to cause brushing over the margin when the sheet is perfect, and then observing the presence or absence of such brushing to separate the perfect from the imperfect sheets. l

6. The herein-described method of testing a sheet of dielectric which consists in sub jecting the intermediate portions only of the sheet to a potential of an order to muse brushing over the margin of the sheet when the latter is perfect, observing the presence or absence of said brushing to separate the bed sheets from the good, said potential be ing applied to the sheet only when the terminals for applying the potential are in en gagement with the sheet.

7. The herein-described. method of testing a sheet of dielectric which consists in placing terminals in engagement with the oppositesides of the sheet with at least one of the terminals spaced inwardly from the edges of the sheet, and then applying potential to the terminals and upon the intermediate portion of the sheet only While said portion of the sheet is engaged by the terminals.

In testimony whereof I have name to this specification.

BYRON MACPHERSON.

signed my 

